Apparatus and method for facilitating fallback access schemes

ABSTRACT

Systems and methodologies are described that facilitate random access procedures using one or more fallback access schemes after initial access attempts have failed. UE equipped to determine failure of a first access request to a first base station due to interference from a second base station. Further, a UE equipped to determine the failure can do so and implement one or more fallback access schemes in response to the determination. In one example, a fallback access scheme allows the UE to select a secondary carrier frequency for communications with the first base station. In another example, a fallback access scheme allows the UE to designate the first base station as inaccessible and communicate with other base stations.

CLAIM OF PRIORITY UNDER 35 U.S.C. §121

The present Application for Patent is a Divisional Application claimingpriority to patent application Ser. No. 13/179,323, filed Jul. 8, 2011,entitled “APPARATUS AND METHOD FOR FACILITATING FALLBACK ACCESS SCHEMES”now allowed, which claims priority to Provisional Application No.61/444,670 entitled “APPARATUS AND METHOD FOR FACILITATING FALLBACKACCESS SCHEMES” filed Feb. 18, 2011, and assigned to the assignee hereofand hereby expressly incorporated by reference herein.

BACKGROUND

1. Field

The present application relates generally to wireless communications,and more specifically to methods and systems for facilitating randomaccess procedures using one or more fallback access schemes afterinitial access attempts have failed.

2. Background

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and so on. Thesesystems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE)systems, time division synchronous code division multiple access(TD-SCDMA) systems and orthogonal frequency division multiple access(OFDMA) systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal communicates with one or more base stations viatransmissions on the forward and reverse links. The forward link (ordownlink (DL)) refers to the communication link from the base stationsto the terminals, and the reverse link (or uplink (UL)) refers to thecommunication link from the terminals to the base stations. Thiscommunication link may be established via a single-in-single-out,multiple-in-signal-out or a multiple-in-multiple-out (MIMO) system.

Further, in time division synchronous code division multiple access(TD-SCDMA) systems, each TD-SCDMA frame may be divided into twosubframes, each consisting of 7 time slots (TSs). In TD-SCDMA systems, auser equipment (UE) may perform a random access procedure to access thenetwork. To facilitate the random access procedure, transmissions on theDL and UL may be aligned to avoid interference. To prevent DL signalcross interference with an uplink signal, a gap time may be used.

Generally, signals transmitted from a first base station may notinterfere with signal reception at a second base station, as the signalsfrom the first base station may be received at the second base stationduring the gap time, or the signal is too weak to interfere with uplinkcommunications. However, in some cases, DL signals from a first basestation may interfere with an uplink transmission slot at a second basestation, and as such, may impede a UEs ability to access the second basestation. Further, as a UE may select a serving base station based on thestrength of DL transmissions, interference on a timeslot used for therandom access procedure may repeatedly prohibit or impede a UE fromaccess the base station.

Currently, when there is interference on a specified uplink channel usedfor access, access requests may be shifted into a traffic channeltimeslot to avoid the interference. Such a process results on reduceduplink capacity for the system due to the fact that some uplink trafficchannel timeslots are used for access transmissions. Further, in anothercurrent implementation, the gap time may be increased. For the samereasons as discussed above, an increase in gap time reduces the overallsystem capacity.

Therefore, there is a need for improved systems and methods forfacilitating UE access procedures when access has failed due tointerference on the uplink channel.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In accordance with one or more aspects and corresponding disclosurethereof, various aspects are described in connection with facilitatingrandom access procedures using one or more fallback access schemes afterinitial access attempts have failed. In one example, UE can be equippedto determine failure of a first access request to a first base stationdue to interference from a second base station. A UE equipped todetermine the failure can do so and implement one or more fallbackaccess schemes in response to the determination. In one example, afallback access scheme allows the UE to select a secondary carrierfrequency for transmission with the first base station. In anotherexample, a fallback access scheme allows the UE to designate the firstbase station as inaccessible and communicate with other base stations.

According to related aspects, a method for facilitating random accessprocedures using one or more fallback access schemes after initialaccess attempts have failed is provided. The method can comprisedetermining failure of a first access request to a first base stationdue to interference from a second base station. The method can alsoinclude implementing one or more fallback access schemes in response tothe determination.

Another aspect relates to a wireless communications apparatus. Thewireless communications apparatus can include at least one processorconfigured to determine failure of a first access request to a firstbase station due to interference from a second base station. Theprocessor is further configured to implement one or more fallback accessschemes in response to the determination.

Yet another aspect relates to a wireless communications apparatus thatfacilitates random access procedures using one or more fallback accessschemes after initial access attempts have failed. The wirelesscommunications apparatus can comprise means for determining failure of afirst access request to a first base station due to interference from asecond base station. The wireless communications apparatus canadditionally include means for implementing one or more fallback accessschemes in response to the determination.

Still another aspect relates to a computer program product, which canhave a computer-readable medium including code for causing at least onecomputer to determine failure of a first access request to a first basestation due to interference from a second base station. Thecomputer-readable medium can also comprise code for causing the at leastone computer to implement one or more fallback access schemes inresponse to the determination.

According to related aspects, a method for facilitating random accessprocedures by a base station is provided. The method can comprisedetermining, by a first base station, a failure to decode a signal froma UE. The method can also include detecting that a signal received froma secondary base station is above an interference threshold. Moreover,the method can include broadcasting, using a primary carrier frequency,one or more secondary carrier frequencies for the UE to use for aninitial access request.

Another aspect relates to a wireless communications apparatus. Thewireless communications apparatus can include at least one processorconfigured to determine, by a first base station, a failure to decode asignal from a UE. The processor is further configured to detect that asignal received from a secondary base station is above an interferencethreshold. Moreover, the processor is configured to broadcast, using aprimary carrier frequency, one or more secondary carrier frequencies forthe UE to use for an initial access request.

Yet another aspect relates to a base station that facilitates randomaccess procedures. The base station can comprise means for determining,by a first base station, a failure to decode a signal from a UE. Thebase station can additionally include means for detecting that a signalreceived from a secondary base station is above an interferencethreshold. Moreover, the base station can include means forbroadcasting, using a primary carrier frequency, one or more secondarycarrier frequencies for the UE to use for an initial access request.

Still another aspect relates to a computer program product, which canhave a computer-readable medium including code for causing at least onecomputer to determine, by a first base station, a failure to decode asignal from a UE. The computer-readable medium can also comprise codefor causing the at least one computer to detect that a signal receivedfrom a secondary base station is above an interference threshold.Moreover, the computer-readable medium can comprise code for causing theat least one computer to broadcast, using a primary carrier frequency,one or more secondary carrier frequencies for the UE to use for aninitial access request

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 depicts a block diagram of a system for facilitating fallbackrandom access procedures in a wireless communication system, accordingto an aspect;

FIG. 2 depicts an example frame structure for a TD-SCMA frame accordingto an aspect;

FIG. 3 depicts an example TD-SCDMA based system with multiple UEscommunicating with a node-B, as time progresses according to an aspect;

FIG. 4 depicts an example UL transmission including interference from ainterfering base station, according to an another aspect;

FIG. 5 depicts an example flowchart of a methodology for facilitatingfallback random access schemes according to an aspect;

FIG. 6 depicts a block diagram of an example user equipment forfacilitating fallback random access schemes according to an aspect;

FIG. 7 depicts a block diagram of an example base station forfacilitating fallback random access schemes according to an aspect;

FIG. 8 depicts an example system for facilitating fallback random accessprocedures in a wireless communication system;

FIG. 9 depicts an example system for facilitating fallback random accessprocedures by a base station; and

FIG. 10 illustrates a block diagram of a design of a base station and aUE in an access network.

DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details.

Generally, when a UE attempts to access a base station, e.g. node-B, theaccess request may be communicated using a limited portion a TS.Further, as noted above, a UE may determine the access attempt hasfailed, and may implement one or more fallback access schemes in orderto minimize facilitate access to a useable base station.

With reference now to FIG. 1, a block diagram of a system 100 forfacilitating fallback access schemes in a wireless communication systemis illustrated. System 100 may include one or more base stations 120,130 (e.g. Node-B, E-Node-B, etc.) and one or more user equipments (UEs)110 (e.g. wireless communications devices (WCD), terminals, etc.), whichcan communicate via respective antennas 126 and 116. In one aspect, atarget base station 120 may conduct a DL communication to UE 110 viaantennas 126. At the UE 110, the DL communications may be used todetermine with which base station a random access procedure may beperformed. In one aspect, UE 120 may receive DL communications receivedvia antennas 116. Further UE 110 may attempt to conduct ULcommunications to target base station 120 via antennas 116 to facilitaterandom access procedures. At the target base station 120, ULcommunications may be received via antennas 126. Further, interferencesignals may also be received from interfering base station 130 that mayimpede processing of an access request from UE 110.

In one aspect of the system, UE 110 may attempt to communicate withtarget base station 120 using a random access procedure facilitatedthrough random access module 112. Such random access communications maybe set up using various parameters determined through random accessmodule 112. In operation, due to interference from interfering basestation 130, the random access procedure may fail to connect with UE 110with the target base station 120.

In another aspect, random access module 112 further includes one or morefallback access schemes 113 to facilitate accessing a base station(e.g., base station 120) after initial access attempts have failed. Insuch an aspect, fallback access schemes may include a secondary carrieraccess scheme 115, an accessible base station access scheme 117, etc.

In one aspect, secondary carrier access scheme 115 may be operable toenable UE 110 to select one of N secondary frequencies used in accessnetwork 100. In such an aspect, the secondary frequency may be selectedto be the secondary frequency that has been measured to have the lowestinterference levels. In another aspect, the secondary frequency may berandomly selected. Generally, since a downlink pilot signal may betransmitted on a primary frequency, secondary frequencies may notexperience other base station downlink communication interference on asecondary frequency. As used herein, a primary frequency may refer to afrequency used by a target base station 120 to transmit a downlink pilotsignal using a downlink pilot channel (DwPCH). Further, any secondaryfrequency of N secondary frequencies may describe any frequency that thetarget base station 120 is not using as a primary frequency. Currently,a UE 110 may transmit and a base station 120 may receive uplink pilotchannel (UpPCH) information on a secondary frequency is supported forhandover procedures. Amendment to the current TD-SCDMA standard maysupport a base station 120 to addition receive UpPCH transmissions forinitial access requests, such as used in a random access procedure.

In operation, once secondary carrier access scheme 115 has selected asecondary frequency, an access request may be transmitted to the targetbase station 120 using the selected secondary frequency. Further, in oneaspect, upon detecting uplink interference on a primary frequency, thetarget base station 120 may transmit secondary frequency information ona broadcast channel. Thereafter, UE 110 may select a secondary frequencyfor performing a random access procedure. In one aspect, the randomaccess procedure may include transmitting an access request on an UpPCHand may receive a response back over a fast physical access channel(FPACH).

In another aspect, an accessible base station access scheme 117 mayenable a UE 110 to remove inaccessible base stations from an initialaccess assessment list. In one such aspect, a base station defined asinaccessible may be removed from an assessment list for a definedduration of time.

In operation, accessible base station access scheme 117 may determinethe UE 110 has failed random access on target base station's 120 primaryfrequency because its UpPCH transmissions have not answered by thenetwork 100. Upon detecting the failure, the UE 110 may internally markthis cell as “inaccessible.” In one aspect, the UE 110 may consider themarked base station 120 to be accessible again upon the expiration of atimer. Further, upon detecting the base station 120 is marked“inaccessible”, the UE 110 may perform base station reselection andselect a base station that is not marked as inaccessible. In one aspect,base station reselection may be based on the reselection criteriaspecified in the current TD-SCMA standard. Thereafter, upon selecting abase station that is not marked as inaccessible, the UE 110 may performa random access procedure with the newly selected base station.

Therefore the proposed systems and methods can assist in allowing a UEto access a base station even where interference impedes initial accessattempts, and as such, may improve overall system performance.

With reference to FIG. 2 an example frame structure of a TD-SCDMA 200 isdepicted. In time division synchronous code division multiple access(TD-SCDMA) systems, each TD-SCDMA frame 200 may be divided into twosubframes 202, each consisting of 7 time slots 204 (TSs). The subframe202 may start with downlink (DL) TSO 206, DwPTS (Downlink Pilot TimeSlot) 208, Gap 210, UpPTS (Uplink Pilot time Slot) 212, and one or moreuplink (UL) TSs 214, and then a few DL TSs. In the depicted exampleaspect, three (3) TSs may be used for UL and four (4) TSs may be usedfor DL. Further, the chip rate in a TD-SCDMA system may be 1.28 Mcps. Assuch, 7 Time Slots (TSs) may be used for the regular traffic andsignaling. The DwPTS may be used for transmitting a pilot signal for thecell. While the UpPTS may be used for the UEs to perform initial randomaccess procedure, and UL synchronization in handover.

Turning now to FIG. 3, an example TD-SCDMA based system 300 withmultiple UEs (304, 306, 308) communicating with a node-B 302, as timeprogresses, is illustrated. Generally, in TD-SCDMA systems, multiple UEsmay share a common bandwidth in communication with a node-B 302.Additionally, one aspect in TD-SCDMA systems, as compared to CDMA andWCDMA systems, is UL synchronization. That it, in TD-SCDMA systems,different UEs (304, 306, 308) may synchronize on the uplink (UL) suchthat all UE (304, 306, 308) transmitted signals arrives at the Node B(NB) at approximately the same time. For example, in the depictedaspect, various UEs (304, 306, 308) are located at various distancesfrom the serving node-B 302. Accordingly, in order for the ULtransmission to reach the node-B 302 at approximately the same time,each UE may originate transmissions at different times. For example, UE308 may be farthest from node-B 302 and may perform an UL transmission314 before closer UEs. Additionally, UE 306 may be closer to node-B 302than UE 308 and may perform an UL transmission 312 after UE 308.Similarly, UE 304 may be closer to node-B 302 than UE 306 and mayperform an UL transmission 310 after UEs 306 and 308. The timing of theUL transmissions (310, 312, 314) may be such that the signals arrive atthe node-B at approximately the same time.

Turning now to FIG. 4, example transmissions from a UE to a targetnode-B and an interfering node-B transmissions are illustrated in anaccess network 400. Depicted in the figure are transmission timing foran interfering node-B 402, a target node-B 404 and a UE 406. As depictedin FIG. 2, a subframe may include a downlink (DL) TSO, Downlink PilotTime Slot (DwPTS) 408, a Gap 410, an Uplink Pilot time Slot (UpPTS) 412,one or more uplink (UL) TSs, and then a few DL TSs. In operation, a UEmay transmit 420 an access request 418 to be received by a target node-Bduring an UpPTS 416. Further, due to factors such as improper networkdesign, propagation delay, etc., a signal transmitted 422 on aninterfering node-B DwPTS may be received during the target node-B UpPTS416. Such interference 422 may impede and/or prohibit a UEs accessrequest 418 transmission 420 from being received and processed by thetarget node-B.

FIG. 5 illustrates various methodologies in accordance with variousaspects of the presented subject matter. While, for purposes ofsimplicity of explanation, the methodologies are shown and described asa series of acts or sequence steps, it is to be understood andappreciated that the claimed subject matter is not limited by the orderof acts, as some acts may occur in different orders and/or concurrentlywith other acts from that shown and described herein. For example, thoseskilled in the art will understand and appreciate that a methodologycould alternatively be represented as a series of interrelated states orevents, such as in a state diagram. Moreover, not all illustrated actsmay be required to implement a methodology in accordance with theclaimed subject matter. Additionally, it should be further appreciatedthat the methodologies disclosed hereinafter and throughout thisspecification are capable of being stored on an article of manufactureto facilitate transporting and transferring such methodologies tocomputers. The term article of manufacture, as used herein, is intendedto encompass a computer program accessible from any computer-readabledevice, carrier, or media.

Turning now to FIG. 5, an example flowchart 500 of a methodology forfacilitating fallback access schemes is illustrated. In one aspect, themethodology may be enabled in various systems, such as a TD-SCDMAsystem, Universal Mobile Telecommunication System time division duplex(UMTS TDD), etc. At block 502, a UE may transmit one or more accessrequests to a target base station as part of a random access procedure.At block 504, the UE may determine the random access procedure hasfailed. In one aspect, the determination may be made after a definednumber of unsuccessful attempts have been performed. Optionally, atblock 506, one or more fallback access schemes may be selected andimplemented by the UE. As used herein, a selection may be implemented invarious ways. In one aspect, the one or more fallback access schemeselection may be predetermined in the UE. In another aspect, the UE maybe configurable to provide a priority to one or more fallback accessschemes over other fallback access schemes. For example, the UE may usean algorithm to determine the optimal approach. In another aspect, theUE may use components of different fallback access schemes. For example,the UE may decide to access the network on the secondary frequency of aneighbor base station. In another aspect, a UE may select only onefallback scheme. In yet another aspect, a UE may be enabled tocontemporaneously implement multiple fallback access schemes. In still afurther aspect, a UE may be enabled to implement multiple fallbackaccess schemes as a series of schemes.

In one example aspect, where a secondary carrier fallback access schemeis selected, at block 508, the UE may select a secondary carrierfrequency to use for a random access procedure. A secondary carrierfallback scheme may be implemented in a system using an N-frequency(e.g., N-Carrier) deployment. An N-Frequency deployment supportsmultiple carriers in TD-SCDMA systems. In an N-frequency deployment, thecarriers may not independent. Among the aggregated carriers, one carriermay be defined as the primary carrier, which carries the broadcastchannel (e.g., BCH mapped to P-CCPCH) in time slot 0. The remainingcarriers may be defined as secondary carriers and system information maynot be broadcasted on these carriers.

Further, besides carrying the broadcast channel, the PCH and FACH onS-CCPCH, as well as DwPCH and PICH may also be transmitted on primaryfrequency only. As such, generally a UE in idle mode may camp on theprimary frequency and RRC connection setup procedures may be initiatedfrom the primary frequency. Further, channel mapping, transmission andreception, power and synchronization control, etc., on each carrier maybe independent of other carriers. Further, traffic channels may betransmitted on any of the N carriers. In one aspect, benefits of reducedfrequency reuse factor in TS0 may include: reduced DwPTS interferencebetween neighboring cells, expanding TS0 and DwPTS coverage, reducedping-pong handovers, etc.

In one aspect, where an N-Frequency deployment is enabled in a HSDPAsystem, radio resources may be assigned on multiple frequencies, and theUE supporting N-Frequency deployment, may have the capability oftransmitting and receiving on multiple frequencies. In another aspect,where N-Frequency deployment is enabled in neighboring TD-SCDMA cells,each cell may transmit BCH (TS0) on just one frequency, e.g., theprimary frequency. Further, by assigning a primary frequency ondifferent frequency points among neighboring cells, a smaller frequencyreuse factor may be achieved.

In such an aspect, the secondary frequency may be selected to be thesecondary frequency that has been measured to have the lowestinterference levels. In another aspect, the secondary frequency may berandomly selected. Generally, since a downlink pilot signal may betransmitted on a primary frequency, secondary frequencies may notexperience other base station downlink communication interference on asecondary frequency. At block 510, the UE may transmit an access requestto a base station using the selected secondary frequency. In one aspect,the random access procedure may include transmitting an access requeston an UpPCH and may receive a response back over a fast physical accesschannel (FPACH).

In another example aspect, where a secondary cell fallback access schemeis selected, at block 512, the UE may designate the base station withwhich the initial access attempt failed as being “inaccessible.” Atblock 514, the UE may perform downlink strength measurements todetermine which BS to attempt to access. In such an aspect, the UE maynot perform measurements on base stations that have been labeled asinaccessible. In one such aspect, a base station defined as inaccessiblemay be removed from an assessment list for a defined duration of time.At block 516, the UE may transmit an access request to a base stationselected from the measurements. In one aspect, base station reselectionmay be based on the reselection criteria specified in the currentTD-SCMA standard.

With reference now to FIG. 6, an illustration of a user equipment (UE)600 (e.g. a client device, wireless communications device (WCD) etc.)that facilitates uplink synchronization during random access proceduresis presented. UE 600 comprises receiver 602 that receives one or moresignal from, for instance, one or more receive antennas (not shown),performs typical actions on (e.g., filters, amplifies, downconverts,etc.) the received signal, and digitizes the conditioned signal toobtain samples. Receiver 602 can further comprise an oscillator that canprovide a carrier frequency for demodulation of the received signal anda demodulator that can demodulate received symbols and provide them toprocessor 606 for channel estimation. In one aspect, UE 600 may furthercomprise secondary receiver 652 and may receive additional channels ofinformation.

Processor 606 can be a processor dedicated to analyzing informationreceived by receiver 602 and/or generating information for transmissionby one or more transmitters 620 (for ease of illustration, only onetransmitter is shown), a processor that controls one or more componentsof UE 600, and/or a processor that both analyzes information received byreceiver 602 and/or receiver 652, generates information for transmissionby transmitter 620 for transmission on one or more transmitting antennas(not shown), and controls one or more components of UE 600. In oneaspect of UE 600, processor 606 may include at least one processor andmemory, wherein the memory may be within the at least one processor 606.By way of example and not limitation, the memory could include on-boardcache or general purpose register.

UE 600 can additionally comprise memory 608 that is operatively coupledto processor 606 and that can store data to be transmitted, receiveddata, information related to available channels, data associated withanalyzed signal and/or interference strength, information related to anassigned channel, power, rate, or the like, and any other suitableinformation for estimating a channel and communicating via the channel.Memory 608 can additionally store protocols and/or algorithms associatedwith estimating and/or utilizing a channel (e.g., performance based,capacity based, etc.). In one aspect, memory 608 may include a basestation assessment list 618 that may be populated with base stationsthat have not been designated as inaccessible.

It will be appreciated that the data store (e.g., memory 608) describedherein can be either volatile memory or nonvolatile memory, or caninclude both volatile and nonvolatile memory. By way of illustration,and not limitation, nonvolatile memory can include read only memory(ROM), programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable PROM (EEPROM), or flash memory. Volatile memorycan include random access memory (RAM), which acts as external cachememory. By way of illustration and not limitation, RAM is available inmany forms such as synchronous RAM (SRAM), dynamic RAM (DRAM),synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhancedSDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).Memory 608 of the subject systems and methods is intended to comprise,without being limited to, these and any other suitable types of memory.

UE 600 can further have random access module 610 that assists the UE 600with initial access to a network. In one aspect, random access module610 further includes one or more fallback access schemes 612 tofacilitate accessing a base station (e.g., base station 120) afterinitial access attempts have failed. In such an aspect, fallback accessschemes may include a secondary carrier access scheme 614, an accessiblebase station access scheme 616, etc.

In one aspect, secondary carrier access scheme 614 may be operable toenable UE 600 to select one of N secondary frequencies used in an accessnetwork. In such an aspect, the secondary frequency may be selected tobe the secondary frequency that has been measured to have the lowestinterference levels. In another aspect, the secondary frequency may berandomly selected. Generally, since a downlink pilot signal may betransmitted on a primary frequency, secondary frequencies may notexperience other base station downlink communication interference on asecondary frequency. In operation, once secondary carrier access scheme614 has selected a secondary frequency, an access request may betransmitted to a target base station (e.g., target base station 120)using the selected secondary frequency. Further, in one aspect, upondetecting uplink interference on a primary frequency, the target basestation may transmit secondary frequency information on a broadcastchannel. Thereafter, UE 500 may select a secondary frequency forperforming a random access procedure.

In one aspect, an accessible base station access scheme 616 may enable aUE 110 to remove inaccessible base stations from an initial accessassessment list 618. In one such aspect, a base station defined asinaccessible may be removed from an assessment list 618 for a definedduration of time. In operation, accessible base station access scheme616 may determine the UE 600 has failed random access on cell's primaryfrequency because all its UpPCH transmissions are not answered by thenetwork. Upon detecting the failure, the UE may internally mark thiscell as “inaccessible.” In one aspect, the UE 600 may consider themarked base station to be accessible again upon the expiration of atimer. Further, upon detecting the base station is marked“inaccessible”, the UE 600 may perform base station reselection andselect a base station that is not marked as inaccessible. In one aspect,base station reselection may be based on the reselection criteriaspecified in the current TD-SCMA standard. Thereafter, upon selectingthe base station that is not marked as inaccessible, the UE 600 mayperform a random access procedure with the newly selected base station.

When sending the RACH message to the network (during the random accessprocedure), the UE shall include downlink signal measurements, whichwill indicate that the UE may not be in the best downlink cell due tothe uplink jamming With this information, the network can allocate theUE to the best downlink cell if the downlink and uplink traffic channeltimeslots on the cell are not jammed In this way, the UE is maintainedat the strongest cell for traffic channels.

Additionally, client device 600 may include user interface 640. Userinterface 640 may include input mechanisms 642 for generating inputsinto WCD 600, and output mechanism 642 for generating information forconsumption by the user of wireless device 600. For example, inputmechanism 642 may include a mechanism such as a key or keyboard, amouse, a touch-screen display, a microphone, etc. Further, for example,output mechanism 644 may include a display, an audio speaker, a hapticfeedback mechanism, a Personal Area Network (PAN) transceiver etc. Inthe illustrated aspects, output mechanism 644 may include a displayoperable to present content that is in image or video format or an audiospeaker to present content that is in an audio format.

With reference to FIG. 7, an example system 700 that comprises a basestation 702 with a receiver 710 that receives signal(s) from one or moreuser devices 116 through a plurality of receive antennas 706, and atransmitter 722 that transmits to the one or more user devices 116through a transmit antenna 708. Receiver 710 can receive informationfrom receive antennas 706 and is operatively associated with ademodulator 712 that demodulates received information. Transmitter 722can transmit information using transmit antennas 708 and is operativelyassociated with a modulator 720 that modulates information fortransmission. Furthermore, base station 702 can receive interferencefrom one or more other base stations 130. In one aspect, such receivedsignals interfere with user devices 116 attempt to initially access basestation 702. Demodulated symbols are analyzed by a processor 714, andwhich is coupled to a memory 716 that stores, among other items,information related to mobile device initial access attempts. Processor714 can be a processor dedicated to analyzing information received byreceiver 710 and/or generating information for transmission by atransmitter 722, a processor that controls one or more components ofbase station 702, and/or a processor that both analyzes informationreceived by receiver 710, generates information for transmission bytransmitter 722, and controls one or more components of base station702. As noted above, base station 702 can additionally comprise memory716 that is operatively coupled to processor 714. It will be appreciatedthat the data store (e.g., memories) components described herein can beeither volatile memory or nonvolatile memory, or can include bothvolatile and nonvolatile memory. By way of illustration, and notlimitation, nonvolatile memory can include read only memory (ROM),programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable ROM (EEPROM), or flash memory. Volatile memory caninclude random access memory (RAM), which acts as external cache memory.By way of illustration and not limitation, RAM is available in manyforms such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronousDRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM(ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM). Thememory 716 of the subject apparatus and methods is intended to comprise,without being limited to, these and any other suitable types of memory.

Processor 714 is further coupled to interference detection module 730.Interference detection module 730 may include primary frequencybroadcast module 732, and secondary frequency access information 734. Inone aspect, base station 702 may receive one or more signals fromvarious sources, such as but not limited to user devices 116 and one ormore other base stations 130. Interference detection module 730 maydetermine a failure to decode a signal from a user device 116. Further,interference detection module 730 may detect that the signal from theuser device 116 is being interfered with by signals being received fromone or more other base stations 130. In such an aspect, interferencedetection module 730 may include secondary frequency access information734 in a broadcast transmitted using a primary frequency broadcastmodule 732 to provide user devices 116 with alternative frequencies touse for initial access.

Referring to FIG. 8, an apparatus 800 that facilitates random accessprocedures using one or more fallback access schemes after initialaccess attempts have failed can reside at least partially within amobile device. It is to be appreciated that apparatus 800 is representedas including functional blocks, which can represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). As such, apparatus 800 includes a logical grouping 802 ofelectrical components that can act in conjunction. For instance, logicalgrouping 802 can include means for determining failure of a first accessrequest to a first base station due to interference from a second basestation (Block 804). For example, in an aspect, the means 804 caninclude random access module 610 and/or processor 606. Further, logicalgrouping 802 can include means for implementing one or more fallbackaccess schemes in response to the determination (Block 806). Forexample, in an aspect, the means 806 can include random access module610 and/or processor 606.

Additionally, apparatus 800 can include a memory 808 that retainsinstructions for executing functions associated with electricalcomponents 804 and 806. While shown as being external to memory 808, itis to be understood that one or more of electrical components 804 and806 can exist within memory 808. In an aspect, for example, memory 808may be the same as or similar to memory 608 (FIG. 6).

Referring to FIG. 9, an apparatus 800 that facilitates random accessprocedures can reside at least partially within a base station. It is tobe appreciated that apparatus 900 is represented as including functionalblocks, which can represent functions implemented by a processor,software, or combination thereof (e.g., firmware). As such, apparatus900 includes a logical grouping 902 of electrical components that canact in conjunction. For instance, logical grouping 902 can include meansfor determining, by a first base station, a failure to decode a signalfrom a UE (Block 904). For example, in an aspect, the means 904 caninclude interference detection module 730 and/or processor 714. Further,logical grouping 902 can include means for detecting that a signalreceived from a secondary base station is above an interferencethreshold (Block 906). For example, in an aspect, the means 906 caninclude interference detection module 730 and/or processor 714.Moreover, logical grouping 902 can include means for broadcasting, usinga primary carrier frequency, one or more secondary carrier frequenciesfor the UE to use for an initial access request (Block 908). Forexample, in an aspect, the means 908 can include interference detectionmodule 730 and/or processor 714.

Additionally, apparatus 900 can include a memory 910 that retainsinstructions for executing functions associated with electricalcomponents 904, 906, and 908. While shown as being external to memory910, it is to be understood that one or more of electrical components904, 906, and 908 can exist within memory 910. In an aspect, forexample, memory 808 may be the same as or similar to memory 716 (FIG.7).

FIG. 10 shows a block diagram of a design of a base station 1010 and aUE 1050. A base station may also be referred to as a Node B, an evolvedNode B (eNB), an access point, etc. A UE may also be referred to as amobile station, a terminal, an access terminal, a subscriber unit, astation, etc. A UE may be a cellular phone, a personal digital assistant(PDA), a wireless modem, a wireless communication device, a handhelddevice, a laptop computer, a cordless phone, etc. In the design shown inFIG. 10, base station 1010 is equipped with K antennas 1034 a through1034 k, and UE 1050 is equipped with R antennas 1052 a through 1052 r,where in general K≧1 and R≧1.

At base station 1010, a transmit processor 1020 may receive data for oneor more UEs from a data source 1012, process (e.g., encode and modulate)the data for each UE based on one or more modulation and coding schemesfor that UE, and provide data symbols for all UEs. Transmit processor1020 may also generate control symbols for control information. Transmitprocessor 1020 may further generate reference/pilot symbols for one ormore reference signals. A MIMO processor 1030 may perform precoding onthe data symbols, the control symbols, and/or the reference symbols, ifapplicable, and may provide K output symbol streams to K modulators(MOD) 1032 a through 1032 k. Each modulator 1032 may process its outputsymbol stream (e.g., for OFDM) to obtain an output sample stream. Eachmodulator 1032 may further condition (e.g., convert to analog, filter,amplify, and upconvert) its output sample stream and generate a downlinksignal. K downlink signals from modulators 1032 a through 1032 k may betransmitted via antennas 1034 a through 1034 k, respectively.

At UE 1050, R antennas 1052 a through 1052 r may receive the K downlinksignals from base station 1010, and each antenna 1052 may provide areceived signal to an associated demodulator (DEMOD) 1054. Eachdemodulator 1054 may condition (e.g., filter, amplify, downconvert, anddigitize) its received signal to obtain samples and may further processthe samples (e.g., for OFDM) to obtain received symbols. Eachdemodulator 1054 may provide received data symbols to a MIMO detector1060 and provide received reference symbols to a channel processor 1094.Channel processor 1094 may estimate the response of the downlink channelfrom base station 1010 to UE 1050 based on the received referencesymbols and may provide a channel estimate to MIMO detector 1060. MIMOdetector 1060 may perform MIMO detection on the received data symbolsbased on the channel estimate and provide symbol estimates, which may beestimates of the transmitted symbols. A receive processor 1070 mayprocess (e.g., demodulate and decode) the symbol estimates based on themodulation and coding scheme(s) used for UE 1050, provide decoded datato a data sink 1072, and provide decoded control information to acontroller/processor 1090.

UE 1050 may estimate the downlink channel response and generate channelfeedback information, which may comprise reported channel vectors. UE1050 may also estimate the downlink channel quality and determinechannel quality indicator (CQI) information. Feedback information (e.g.,the channel feedback information, CQI information, etc.), data from adata source 1078, and a reference signal may be processed (e.g., encodedand modulated) by a transmit processor 1080, precoded by a MIMOprocessor 1082, if applicable, and further processed by modulators 1054a through 1054 r to generate R uplink signals, which may be transmittedvia antennas 1052 a through 1052 r. At base station 1010, the R uplinksignals from UE 1050 may be received by K antennas 1034 a through 1034 kand processed by demodulators 1032 a through 1032 k. A channel processor1044 may estimate the response of the uplink channel from UE 1050 tobase station 1010 and may provide a channel estimate to MIMO detector1036. MIMO detector 1036 may perform MIMO detection based on the channelestimate and provide symbol estimates. A receive processor 1038 mayprocess the symbol estimates, provide decoded data to a data sink 1039,and provide decoded feedback information to a controller/processor 1040.Controller/processor 1040 may control data transmission to UE 1050 basedon the feedback information.

Controllers/processors 1040 and 1090 may direct the operation at basestation 1010 and UE 1050, respectively. Processor 1094, processor 1090and/or other processors and modules at UE 1050 may perform or directprocess 500 in FIG. 5, and/or other processes for the techniquesdescribed herein. Processor 1044, processor 1040 and/or other processorsand modules at base station 1010 may also perform or direct process 500in FIG. 5, and/or other processes for the techniques described herein.Memories 1042 and 1092 may store data and program codes for base station1010 and UE 1050, respectively. A scheduler 1046 may select UE 1050and/or other UEs for data transmission on the downlink and/or uplinkbased on the feedback information received from the UEs.

In one aspect processor 1090 may be operable to provide means fordetermining failure of a first access request to a first base stationdue to interference from a second base station, and means forimplementing one or more fallback access schemes in response to thedetermination. In another aspect, processor 1090 may provide means fordetecting a first access request has fails more than a threshold numberof times. In another aspect, processor 1090 may provide means forselecting a secondary carrier frequency for the first base station, andmeans for transmitting a second access request to the first base stationusing the selected secondary carrier frequency. In another aspect,processor 1090 may provide means for measuring uplink interferencelevels for at least two secondary carrier frequencies used by the firstbase station, and means for selecting the secondary carrier frequency asthe one of the at least two secondary carrier frequencies having a lowerinterference level. In one such aspect, the processor may furtherprovide means for randomly selecting the secondary carrier frequencyfrom two or more secondary carrier frequencies. In another aspect,processor 1090 may provide means for detecting failure of the secondaccess request on the selected secondary carrier frequency, means forselecting a different secondary carrier frequency used by the first basestation, and means for transmitting a third access request to the firstbase station using the selected different secondary carrier frequency.In another aspect, processor 1090 may provide means for receivingsecondary carrier frequency information on a broadcast channel from thefirst base station, and means for selecting the secondary carrierfrequency based on the received secondary carrier frequency information.In another aspect, processor 1090 may provide means for detectingfailure of the second access request on the selected secondary carrierfrequency, means for designating the first base station as inaccessible,and means for measuring downlink strengths from one or more other basestations, wherein a base station designated as inaccessible is notincluded in the measuring. In another aspect, processor 1090 may providemeans for designating the first base station as inaccessible, means formeasuring downlink strengths from one or more other base stations,wherein a base station designated as inaccessible is not included in themeasuring, means for determining the one of the other base stationshaving the strongest downlink signal strength, and means fortransmitting a second access request to the determined one other basestation. In another aspect, processor 1090 may provide means fordesignating the first base station as inaccessible for a definedduration of time.

In one aspect processor 1040 may be operable to provide means fordetermining, by a first base station, a failure to decode a signal froma UE, means for detecting that a signal received from a secondary basestation is above an interference threshold, and means for broadcasting,using a primary carrier frequency, one or more secondary carrierfrequencies for the UE to use for an initial access request. In anotheraspect, processor 1040 may provide means for receiving, using at leastone of the one or more secondary carrier frequencies, the initial accessrequest from the UE, and means for processing the initial accessrequest. In another aspect, processor 1040 may provide means forreceiving, by the first base station, signals from the UE and the secondbase station.

As used in this application, the terms “component,” “module,” “system”and the like are intended to include a computer-related entity, such asbut not limited to hardware, firmware, a combination of hardware andsoftware, software, or software in execution. For example, a componentmay be, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution, a program,and/or a computer. By way of illustration, both an application runningon a computing device and the computing device can be a component. Oneor more components can reside within a process and/or thread ofexecution and a component may be localized on one computer and/ordistributed between two or more computers. In addition, these componentscan execute from various computer readable media having various datastructures stored thereon. The components may communicate by way oflocal and/or remote processes such as in accordance with a signal havingone or more data packets, such as data from one component interactingwith another component in a local system, distributed system, and/oracross a network such as the Internet with other systems by way of thesignal.

Furthermore, various aspects are described herein in connection with aterminal, which can be a wired terminal or a wireless terminal Aterminal can also be called a system, device, subscriber unit,subscriber station, mobile station, mobile, mobile device, remotestation, remote terminal, access terminal, user terminal, terminal,communication device, user agent, user device, or user equipment (UE). Awireless terminal may be a cellular telephone, a satellite phone, acordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, a computingdevice, or other processing devices connected to a wireless modem.Moreover, various aspects are described herein in connection with a basestation. A base station may be utilized for communicating with wirelessterminal(s) and may also be referred to as an access point, a Node B, orsome other terminology.

Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom the context, the phrase “X employs A or B” is intended to mean anyof the natural inclusive permutations. That is, the phrase “X employs Aor B” is satisfied by any of the following instances: X employs A; Xemploys B; or X employs both A and B. In addition, the articles “a” and“an” as used in this application and the appended claims shouldgenerally be construed to mean “one or more” unless specified otherwiseor clear from the context to be directed to a singular form.

The techniques described herein may be used for various wirelesscommunication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, TD-SCDMAand other systems. The terms “system” and “network” are often usedinterchangeably. A CDMA system may implement a radio technology such asUniversal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includesWideband-CDMA (W-CDMA) and other variants of CDMA. Further, cdma2000covers IS-2000, IS-95 and IS-856 standards. A TDMA system may implementa radio technology such as Global System for Mobile Communications(GSM). An OFDMA system may implement a radio technology such as EvolvedUTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, Flash-OFDM™, etc. UTRA and E-UTRA are partof Universal Mobile Telecommunication System (UMTS). 3GPP Long TermEvolution (LTE) is a release of UMTS that uses E-UTRA, which employsOFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTEand GSM are described in documents from an organization named “3rdGeneration Partnership Project” (3GPP). Additionally, cdma2000 and UMBare described in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). Further, such wireless communicationsystems may additionally include peer-to-peer (e.g., mobile-to-mobile)ad hoc network systems often using unpaired unlicensed spectrums, 802.xxwireless LAN, BLUETOOTH and any other short- or long-range, wirelesscommunication techniques.

Various aspects or features will be presented in terms of systems thatmay include a number of devices, components, modules, and the like. Itis to be understood and appreciated that the various systems may includeadditional devices, components, modules, etc. and/or may not include allof the devices, components, modules etc. discussed in connection withthe figures. A combination of these approaches may also be used.

The various illustrative logics, logical blocks, modules, and circuitsdescribed in connection with the aspects disclosed herein may beimplemented or performed with a general purpose processor, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but, in the alternative, the processor may be any conventionalprocessor, controller, microcontroller, or state machine. A processormay also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. Additionally, at least oneprocessor may comprise one or more modules operable to perform one ormore of the steps and/or actions described above.

Further, the steps and/or actions of a method or algorithm described inconnection with the aspects disclosed herein may be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. A software module may reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a harddisk, a removable disk, a CD-ROM, or any other form of storage medium,and/or computer readable medium known in the art. An example storagemedium may be coupled to the processor, such that the processor can readinformation from, and write information to, the storage medium. Anexample computer readable medium may include memory. Further a computerprogram product may include a computer readable medium and itspackaging. In the alternative, the storage medium may be integral to theprocessor. Further, in some aspects, the processor and the storagemedium may reside in an ASIC. Additionally, the ASIC may reside in auser terminal. In the alternative, the processor and the storage mediummay reside as discrete components in a user terminal Additionally, insome aspects, the steps and/or actions of a method or algorithm mayreside as one or any combination or set of codes and/or instructions ona machine readable medium and/or computer readable medium, which may beincorporated into a computer program product.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored or transmitted as one or moreinstructions or code on a computer-readable medium. Computer-readablemedia includes both computer storage media and communication mediaincluding any medium that facilitates transfer of a computer programfrom one place to another. A storage medium may be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionmay be termed a computer-readable medium. For example, if software istransmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, DSL, orwireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs usually reproduce data optically withlasers. Combinations of the above should also be included within thescope of computer-readable media.

While the foregoing disclosure discusses illustrative aspects and/orembodiments, it should be noted that various changes and modificationscould be made herein without departing from the scope of the describedaspects and/or embodiments as defined by the appended claims.Furthermore, although elements of the described aspects and/orembodiments may be described or claimed in the singular, the plural iscontemplated unless limitation to the singular is explicitly stated.Additionally, all or a portion of any aspect and/or embodiment may beutilized with all or a portion of any other aspect and/or embodiment,unless stated otherwise.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

What is claimed is:
 1. A method of wireless communications, comprising:determining, by a first base station, a failure to decode a signal froma user equipment (UE); detecting that a signal received from a secondarybase station is above an interference threshold; and broadcasting, usinga primary carrier frequency, one or more secondary carrier frequenciesfor the UE to use for an initial access request.
 2. The method of claim1, further comprising: receiving, using at least one of the one or moresecondary carrier frequencies, the initial access request from the UE;and processing the initial access request.
 3. The method of claim 1,further comprising: receiving, by the first base station, signals fromthe UE and the second base station.
 4. The method of claim 1 wherein theinterference threshold comprises a value above which communications withthe UE are interfered with above a connection threshold percentage.
 5. Acomputer program product, comprising: a computer-readable mediumcomprising code for: determining, by a first base station, a failure todecode a signal from a UE; detecting that a signal received from asecondary base station is above an interference threshold; andbroadcasting, using a primary carrier frequency, one or more secondarycarrier frequencies for the UE to use for an initial access request. 6.The computer program product of claim 5, wherein the computer-readablemedium further comprises code for: receiving, using at least one of theone or more secondary carrier frequencies, the initial access requestfrom the UE; and processing the initial access request.
 7. The computerprogram product of claim 5, wherein the computer-readable medium furthercomprises code for: receiving, by the first base station, signals fromthe UE and the second base station.
 8. The computer program product ofclaim 5, wherein the interference threshold comprises a value abovewhich communications with the UE are interfered with above a connectionthreshold percentage.
 9. An apparatus, comprising: means fordetermining, by a first base station, a failure to decode a signal froma UE; means for detecting that a signal received from a secondary basestation is above an interference threshold; and means for broadcasting,using a primary carrier frequency, one or more secondary carrierfrequencies for the UE to use for an initial access request.
 10. Theapparatus of claim 9, further comprising: means for receiving, using atleast one of the one or more secondary carrier frequencies, the initialaccess request from the UE; and means for processing the initial accessrequest.
 11. The apparatus of claim 9, further comprising: means forreceiving, by the first base station, signals from the UE and the secondbase station.
 12. The apparatus of claim 9 wherein the interferencethreshold comprises a value above which communications with the UE areinterfered with above a connection threshold percentage.
 13. Anapparatus for wireless communications, comprising: at least oneprocessor configured to: determine a failure to decode a signal from auser equipment (UE); detect that a signal received from a secondary basestation is above an interference threshold; and broadcast, using aprimary carrier frequency, one or more secondary carrier frequencies forthe UE to use for an initial access request.
 14. The method of claim 13,wherein the at least one processor is further configured to: receive,using at least one of the one or more secondary carrier frequencies, theinitial access request from the UE; and process the initial accessrequest.
 15. The method of claim 13, wherein the at least one processoris further configured to: receive signals from the UE and the secondbase station.
 16. The apparatus of claim 13 wherein the interferencethreshold comprises a value above which communications with the UE areinterfered with above a connection threshold percentage.